Electric cable system



Dec. 1, 1936.

n ETH C. E. BENNETT ELECTRIC CABLE SYSTEM Filed June S, 1934 n glmlw E 2 Sheets-Sheet l Patented Dec. l, 1936 UNITEDA STATES PATENT oEFlcE ELECTRIC CABLE SYSTEM Charles E. Bennett, Ridgewood, N. J., assignor to The Okonite-Callender Cable Company, Incor- `l'rorated, Paterson, N. J., a corporation of New ersey Application June 8, 1934, Serial No. 729,607

3 Claims. (Cl. 247-3) .This invention relates to cable systems of the sealed an insulator Il, each of the cables l, 2 type in which the insulated unsheathed cable and 3 extending through an outlet pipe, riser and conductors are enclosed in a pipe filled with oil into the insulator Il. This construction emmaintained under a high pressure, say, for exployed within each of the insulators Il may be ample, 200 pounds to the square inch, but in any the same as that disclosed in my copending apevent under suliiciently high pressure to increase plication above referred to. Inasmuch as the the dielectric strength of the oil, and has for one outlet pipes, risers and insulators are in comof its objects the' provision in such a system, munication with the pipe line it will be appreciparticularly at the terminals thereof current ated that each cable to its outer end is subtr-ansformers and coupling condensers adapted to merged in oil under high pressure. be connected to instruments such as relays or Each of the cables l, 2 and 3 is provided with other burden and to synchronizing and potential shielding tape designated i3. Within each riser indicators, etc. lll and submerged in the oil therein is a current A further object of my invention is the provitransformer i2 each insulated shielded cable sion of a construction which is relatively inpassing through the transformer. in each inexpensive as compared with prior systems, and stance the shielding tape i3 is discontinuedashort very compact so as to occupy only the minimum distance above the top ci" each transformer as of space. shown at it, the tape about the remainder oi A still further object of my invention is the the cable and which I have designated l5 being installation of current transformers and couseparated from the tape i3 by several layers oi pling condensers directly in the terminal strucvarnished cambric i@ or other suitable insulating ture oi a cable system such as I have above briefly material. referred to. Adjacent each of the transformers l2 each of Terminal structures such as disclosed in my the risers i8 is provided with a lateral outlet il. copending application Serial No. 631,442, filed Each of these outlets is provided with a barrier September 2, 1932, for example, are very Well i8 which isabakelite disc, for example, the leads adapted for use in connection with the practice it :from the transformers passing through these oi my invention. discs liquid-tight to the outer side of the discs in the drawings accompanying this applicawhere they will be connected to rubber covered tion: or other type ll@ volt wire running to measuring Fig. i is a part sectional elevational view showinstruments or other burden which are operated ing an embodiment of lmy invention; by current from the transformer.

2 is Section 0n 'the line 2 2 0f F18- l; This provides a very simple and er'dcient con- 3 iS a SECOXISJI elevational View 0f the struction particularly useful with cable systems structure providing the condenser coupling shown of the type in which the nsuated Came conon a smaller scale 1n Fig: l; and ductors are maintained submerged in oil under F1@ 4 1S a modlcatlon of the structure of high pressure, the transiormers i2 as will be ap- Fg- 3 L preciated being likewise submerged in this oil at Referrmg o the dragm in. dtfuldte m" all times so as to benet by the high'pressure at sulated unsheathed con uc rs an of a which the same is kept.

three phase cable system are enclosed in a pipe line 4 of steel, iron, or other suitable materiali t it is be undefsmog that thee mmm? "f leid? capable of containing the oil 5 under high presa enf mm the Taps Omers 2 @ay van@ Sure Say, for example, 200 pounds to the square to suit various cond1tions and 1t will be appreciinch or even highen ated, iurtnermore, that whlle I have mentioned the barrier discs i8 as being composed of bake- Secured to the pipe line 4 is a terminal manih iold 5 constituting in effect a continuation of the lite, other mate'l'als may be employed, if desired, even metal in which latter event hushed pipe line. This manifold is equipped with outiet pipes 1, 8 and 9 which may conveniently be connections would be employed at the barriers From all of the foregoing it will be seen that integral with the manifold 6. An outlet pipe is I have provided current transformers in connecprovided for each cable conductor as will be apparent from the drawings. tion with a power cable system wherein the trans- A riser designated I is sealed liquid-tight to formers surround the cable conductors and are conveniently installed directly in the cable ter..

the outer end of each of the outlet pipes l, 8 and s. To the outer end of each of the risers lo is mmals, thereby providing transformers compara- 2 aoeaaeo ble in size and characteristics to ordinary laboratory type instruments.

Prior to my invention and especially in high voltage service it has been necessary to build special transformers and bushings to take care of the means for measuring currents, these transformers and bushings being of great size and very expensive as compared to the present invention. Furthermore, 1n prior structures the magnetic ileld is necessarily considerably removed from the cable conductor so that the transformers are not nearly as eillcient as in the structure provided by the present invention.

As above mentioned one of the objects of the present invention is to provide coupling condensers in the cable terminals, thereby obtaining a very compact and inexpensive construction and eliminating the expense incident to prior structures where condensers of different capacities must be purchased for different installations, the present construction being such as to provide for any desired capacity in the device itself. More specincally, I propose to employ the conductor of the power cable as one plate of a condenser, the shielding tape of the power cable functioning as the other plate of the condenser. It will be evident by varying the effective length of this shielding tape any desired capacity can be obtained.

Referring more particularly to Fig. 3 it will be seen that the shielding tape I5 for each conductor is split into sections, insulated from each other by insulators 20 so as' to provide a short length 2| of shielding tape within the terminal riser insulated from the cable conductor and from the remainder of the shielding tape as well as from the risers i0. This short length of shielding tape constitutes one plate of my condenser the other plate, as above mentioned, being provided by the conductor itself. Obviously by varying the length of the shielding section or condenser plate 2| the capacity of the condenser may be varied to any extent desired. This is of great economical and practical advantage as compared with prior structures where it is necessary to purchase and install a separate condenser wherel condensers of different capacities arel desired.

About the sheath length or plate 2i I provide a connector 22 which passes through an insulator 23 in an outlet 24 from each of the risers i0 to the transformer, shown diagrammatically at 25, which is of standard construction in instrument work such as for synchronizing and potential indicators. The leads from the transformer 25 to any burden are shown at 26.

I might mention that while the transformer 25 is enclosed in oil it is not necessary that this oil shall be under the pressure at which the oil in the cable is maintained, the disc 2l, shown in the connection between the transformer and the riser l0 being in the nature of a barrier disc.

In Fig. 4 I have shown a slight variation from the construction shown in Fig. 3. In this showing the shielding length 2i is insulated from the rest of the shielding by discontinuing the shielding, as in the case of Fig. 3', and employing insulating tape 28 as the insulating means. as distinguished from the insulators 20 of Fig. 3.

Prior to my invention it has been usual to employ special capacity couplings to connect the special transformer 25 with the high voltage line. Such special apparatus, however, is only capable of delivering very small quantities of power, in the neighborhood, for example, of 60 voltamperes, while in my construction any amount of power within reason may be delivered. which may be in the neighborhood of ten times that just mentioned. With my construction the size of the'cable bushing is not increased nor does my construction necessitate any additional room.

It is to be understood that changes may be made, in the details of construction above described within the purview of this invention.

What I claim is:-

1. In a cable system, the combination of a pipe line, an insulated cable conductor disposed therein, oil under pressure in the pipe line in which the cable is immersed, grounded shielding tape about the insulation of the cable, an outlet and riser freely communicating with the pipe line, a terminal carried by the riser, the cable extending through the outlet and riser into said terminal, a transformer within the riser submerged in the high pressure oil therein, and immediately surrounding the said shielding tape, and a lead for said transformer extending liquid tight to the exterior of the riser.

2. In a cable system, the combination of a pipe line, an insulated cable conductor disposed therein, oil under pressure in the pipe line in which the cable is immersed, grounded shielding tape about the insulation of the conductor, an outlet and riser freely communicating with the pipe line, a terminal carried on the outer end of the riser, a transformer Within the riser, immersed in the high pressure oil therein, said cable extending through the outlet, riser and transformer to said terminal, the transformer immediately surrounding said shielding tape.

3. In a cable system, the combination of a pipe line, insulated unsheathed cables loosely disposed in said pipe line, grounded shielding tape about the insulation of the cable, a manifold secured to and constituting a continuation of said pipe line, outlets for said manifold, risers secured liquid tight to each outlet, a terminal insulator secured liquid tight to each riser, the insulated unsheathed cable conductors extending through the outlets and risers to the outer ends of said terminal insulators, said outlets and risers being in free communication with each other and through the manifold with the pipe line, oil under high pressure in said pipe line, manifold, outlets and risers, in which the insulated cable conductors are immersed, and a transformer within each riser submerged in the high pressure oil therein and immediately surrounding the shielding tape of the cable.

CHARLES E. BENNETT. 

